Modes of producing lithium-ion batteries (“Li-ion batteries”) presented in numerous articles and patents are known; the work “Advances in Lithium-Ion Batteries” (ed. W. van Schalkwijk and B. Scrosati), published in 2002 (Kluever Academic/Plenum Publishers) provides a good review of the situation. The electrodes of Li-ion batteries may be produced by means of printing or deposition techniques known to a person skilled in the art, and in particular by roll-coating, doctor blade or tape casting.
All-solid thin-layer Li-ion batteries having a planar architecture, i.e. which are essentially comprised of a set of three layers forming a basic battery cell: an anode layer and a cathode layer separated by an electrolyte layer are also known.
They use metallic lithium anodes and lithium phosphorus oxynitride films as the electrolyte. However, significant variations in volume of the lithium anode in charging and discharging steps makes it extremely difficult to properly encapsulate the battery without the risk of loss of tightness of the encapsulation.
More recently, new all-solid battery architectures consisting of a stack of thin layers have been proposed. These batteries consist of a rigid and monobloc assembly of basic cells connected in parallel. These batteries use dimensionally stable anodes to ensure the efficacy of the encapsulation, and enable three-dimensional structures to be produced, with better surface energy densities than the planar architectures. Such batteries are described in documents WO 2013/064779 A1 or WO 2012/064777 A1. The batteries described in these documents do not contain organic solvent-based liquid electrolyte, their structure consists of all-solid thin layers, without porosity in the electrode layers in order to ensure good properties of stability of the battery over time. The process for producing these batteries, also described in documents WO 2013/064779 A1 or WO 2012/064777 A1, has numerous advantages because it makes it possible to produce multilayer, thin-layer and therefore relatively non-resistant assemblies, enabling performance in terms of power to be preserved.
However, in some cases, the process of producing such batteries may have some limits according to the materials used, in particular for the electrolyte. In fact, ionic conductive glasses may be difficult to implement. For example, solid electrolytes such as LiPON or lithiated borates have a relatively low glass transition temperature, generally between around 250 and 300° C.: thus, during the step of assembly of the battery by pressurized annealing of the different layers, the electrolyte materials may partially crystallize, which may modify their ionic conduction property. Similarly, when the solid lithium phosphorus-based electrolyte is used, it may be beneficial to differentiate the chemical compositions of the electrolytes in contact with the anodes and cathodes in order to optimize the performance of the electrolytes.
However, the use of two lithium phosphorus-based electrolyte formulations deposited on each of the faces of the electrodes may lead to the appearance of new phases at the interface between the two electrolyte layers to be assembled, and may therefore modify the conduction properties.
Similarly, solid Li7La3Zr2O12 (called LLZO) electrolytes are good ionic conductors and are very stable in contact with anodes and cathodes, but their highly refractory character makes it sometimes difficult to weld, at low temperature, the electrodes to one another via the electrolyte layer without causing an interdiffusion phenomenon at the interfaces with the electrodes.